Sidebar displacement?

Hello,
I apologize in advance if the answer to this question seems obvious, but I'm fairly computer illiterate and have relied mostly on friends with knowledge of CSS while setting up my blog. I have a problem with the sidebar on my page (http://veganeatsblog.com). The blogroll and all of the widgets and stuff used to be placed within the white-coloured middle area of the page, fitting in directly beside the content area. Well, a few weeks ago, I noticed that all of a sudden it began appearing outside of the white content area and in the gray-coloured side part to the right of the page. Why did it do this and more importantly, how do I get back to the original set up?

If it was a problem in a post, then clicking on each title would reveal which post causes the issue; but the sidebar remains displaced no matter which post you isolate. The source code of the sidebar items is ok too, as far as I can tell. So it's probably some mistake in your CSS.